Viking invasions of England

The Viking invasions of England occurred from 865 to 1066, during which the Scandinavian Vikings launched several invasions against the Anglo-Saxon kingdoms of England, following almost a century of raids and colonization of the British Isles. The era of invasions started with the arrival of the Great Heathen Army in 865, and it ended with the Battle of Stamford Bridge in 1066, in which King Harald Hardrada was defeated and killed during the Norsemen's last attempt at claiming the English throne.

Background
In 410, the Roman Empire pulled out of Britannia and left in its wake a patchwork of Britonnic and Romano-Britonnic peoples. The Picts attacked from beyond Hadrian's Wall, Irish warriors moved in from the west, and Angles, Saxons, Jutes, and Frisians moved from mainland Europe onto the east of the island. These incoming Germanic tribes replaced the Romano-Britons and Britons on the east of the island by the end of the 7th century, forming the seven kingdoms of Wessex, Mercia, Northumbria, East Anglia, Kent, Sussex, and Essex. The kingdoms all eventually converted to Christianity, but they continued to fight among themselves and their neighbors.

Across the North Sea in Scandinavia, pagan and warlike seafaring peoples related to the Anglo-Saxons were compelled by a combination of popular pressure, Frankish aggression from the south, and a revolution in shipbuilding techniques to look outwards from Scandinavia at the end of the 8th century. Soon, the frist Scandinavian ships were sighted off Britain, and they became known as "Vikings" due to their piracy. The Vikings focused on attacking Christian holy sites, which tended to yield the best monetary rewards, plundering northern Britain and Ireland. However, their tactics began to change, and the most ambitious began to over-winter in Britain, with Norwegian settlers coming to replace or subjugate the existing populations of the Faroe Islands, Orkney, Shetland, and in areas of Ireland.

Gradually, Mercia lost its dominance during the early 9th century and was replaced by Wessex under its king Egbert, a shrewd leader who had been educated across the English Channel in Francia. He was all too familiar with the Vikings, fighting a number of battles against him, most notably at the Battle of Carhampton in 836. He conquered the minor kingdoms of Essex, Sussex, and Kent during his reign, firmly establishing Wessex as the most powerful Anglo-Saxon kingdom.

Great Heathen Army
In 865, Aethelred of Wessex became king. That same year, a vast armada of hundreds Viking longships appeared off the coast of East Anglia (carrying Vikings from Ireland, Frisia, Francia, Scandinavia, and Pictland, making landfall near Thetford. The invasion fleet was commanded by Ragnarr Lodbrok's sons Halfdan Whiteshirt, Ivar the Boneless, and Ubbe Ragnarrsson, who had come to England to avenge the death of their father, killed by King Aella of Northumbria.

After landing in East Anglia, the Vikings forced King Edmund of East Anglia to give them horses and supplies before marching north to capture the capital of Northumbria, York. Northumbria became a bastion of Scandinavian culture for the next two centuries. After ravaging Northumbria, the army again went on the move, gathering more warriors to their banners from all over the Scandinavian world as word spread of their victories. They marched south into Mercia and captured the town of Nottingham, and King Burghred of Mercia called Wessex for support. However, Ivar remained inside the walls of Nottingham, and Burghred bribed Ivar to leave. The Mercian and West Saxon armies then disbanded to plow their fields, and the Vikings moved back to Jorvik for the winter, considerably richer.

Anglo-Saxon counterattack
In the new year, the Vikings returned to East Anglia, stamped out the kingdom entirely, martyred Edmund, and turned it into another Danish foothold. In 870, the army split, with some remaining in Northumbria and East Anglia, as Ivar led the other half to conquer Alt Clud in southern Scotland. King Halfdan then led a part of the army south, bypassing Mercia entirely, to rage deep into Wessex. Halfdan and the warlord Bagsecg fortified the town of Reading and repelled an Anglo-Saxon counterattack led by King Aethelred and his brother Alfred on 4 January 871, but they were defeated at the Battle of Ashdown in Berkshire four days later, with Bagsecg dying in battle. After Aethelred died that April from wounds received in battle, Alfred became the new king, and he bribed Halfdan to withdraw. Halfdan returned to become King of Northymbre in Jorvik, while his general Guthrum became the King of East Engle.

By 871, the ruling dynasties of East Anglia and Northumbria had been swept away and conquered, Mercia's east was overrun by marauding Scandinavians, various Pictish rulers fought on to maintain their independence, and the Anglo-Saxon kingdom of Wessex was the last bastion of Anglo-Saxon resistance. However, Alfred knew that, sooner or later, the Vikings would be back. Ivar and his Dubliner sea king ally Olaf the White were busy in the north, having taken Alt Clud's capital of Dumbarton Rock in 870 after massacring its defenders, razing its citadels, and enslaving its inhabitants for sale in Dublin and York. Ivar then retired, and he would not reappear on English shores again. However, Ivar and Olaf's descendants in Dublin continued to play a huge role in Britain and Ireland for centuries to come.

Great Summer Army
Meanwhile, Halfdan headed north to Northumbria with 1,000 veterans, dividing the lands between his men and plowing the fields; the Norse began to colonize Jorvik. Meanwhile, in East Anglia, Guthrum - the commander of the Great Summer Army - decided to collaborate with Halfdan's warriors in Northumbria to carve up the severely weakened Mercia. In 874, King Burghred was forced to flee into exile in Wessex, and the Vikings set up Ceolwulf of Mercia as a puppet ruler.

Wessex now stood alone, the last Anglo-Saxon kingdom not to fall. In 875, the Vikings started to test the defenses of Alfred's kingdom, with small fleets of 5-6 vessels raiding Wessex from all directions. Alfred relied on the fyrd, an army of seasonal levies (consisting of poorly-armed farmers and his personal retinue of a few hundre men), while Guthrum had thousands of hardened warriors in his army. In 876, Guthrum invaded Wessex with a large host of mounted warriors, and he seized the important regional town of Wareham after defeating Alfred's army. The two sides agreed to peace to buy time, and, the next spring, Guthrum headed even further to the west, targeting Exeter, which drew Alfred away from a second threat under Ubbe Ragnarrsson. Ubbe's Irish and Frisian Vikings over-wintered on the south coast of Wales, but, as it made its way along the north coast of Devon aboard 120 longboats, the fleet was destroyed by a massive storm off the coast of Dorset, leaving their survivors to limp back to their base in southern Wales. Guthrum retreated to Gloucester in southern Mercia, but Alfred was still beset on all sides by bloodthirsty raiders.

On 6 January 878, in the midst of the important Christmas festival, Guthrum suddenly appeared at Alfred's royal estate at Chippenham with his best outriders, launching a surprise attack in conjunction with treacherous West Saxon ealdormen. Alfred barely escaped with a handful of followers while Guthrum sent his warriors in swift pursuit. Alfred fled west into the marshlands of the Somerset Levels, a vast area of undrained boggy wetlands where he had spent much of his time as a youth. He set up his base on the island Athelney, where he prepared to make a final stand with just a few hundred followers. Guthrum stood on the brink of becoming king in all of southern England, but Alfred launched raids into his own kingdom, now overrun by Guthrum's warriors. Ubbe returned to Wessex to take part in the division of the kingdom, this time with only 23 ships. He landed in northern Devon near the fortress of Arx Cynuit, hoping to launch a pincer movement against Alfred. However, he was met at Arx Cynuit by Ealdorman Odda of Devon, who had levied his fyrdmen to drive out the invaders. At Cynwit, Ubbe was struck down in battle.

Guthrum was left overextended by Ubbe's demise at Cynwit, so Alfred and his ealdormen broke up Guthrum's supply lines and lines of communication. Alfred called as many of the fyrdmen of Somerset, Wiltshire, and Hampshire as he could, and, for three days from 4 to 7 May, they waited at Egbert Stone for their warriors to arrive from all corners of the kingdom. Soon, several thousand levies and a few hundred professional household soldiers were rallied, and Alfred engaged Guthrum's warriors at the Battle of Edington. For a whole day, the two shield walls fought until the smaller Danish force broke and fled to Chippenham. The West Saxons killed every Dane who did not make it inside the fortress, and Guthrum was besieged for two weeks before surrendering. Guthrum surrendered hostages and promised to leave Wessex for good, and the Vikings even had Guthrum baptized as a Christian, convincing Alfred that the Vikings would keep their word. The Danes finally pulled out of Wessex entirely, retreating to East Anglia, where Guthrum became king. In 886, Guthrum and Alfred divided Mercia between the Anglo-Saxon west and the Danish east. Alfred was now in a strong position, and, by and large, Guthrum would keep the peace, giving Alfred the ability to fortify his country against further invasions from overseas.

War for England
Alfred spent the 880s converting the various market towns of his kingdom into burhs, fortified safe havens and meeting places for local militias. He also formed a lasting alliance with Aethelred of Mercia, a warlord who ruled over the Anglo-Saxion portion of Mercia after Ceolwulf's death in 879, and married Alfred's daughter Aethelflaed. Alfred also achieved a similar arrangement with the southern Welsh kingdoms, whose rulers were hemmed in by the expansionist sons of Rhodri the Great in Gwynedd and Powys. The most powerful of the northern Welsh kings, Anarawd ap Rhodri, allied himself with the Vikings of Jorvik against Wessex before ultimately accepting Anglo-Saxon vassalage.

Guthrum died in 890, and, just two years later, the burh system faced its first real test when two massive fleets of 300 longships under Hastein arrived off Kent. Wessex held out, and, by 896, Hastein's men either left Britain entirely or dispersed into East Anglia. Alfred's eldest son and heir Edward took the throne, but Alfred's nephew Aethelwold contested the throne. Aethelwold fled into Northumbrian Danelaw, where he was enthusiastically accepted by the local rulers, who were intent on finally conquering Wessex. In 901, Aethelwold and a large army sailed south to Wessex, and, joining up with Eohric of East Anglia, he invaded Mercia. He forced Aethelred and Aethelflaed to flee to Wessex, but Edward forced the Danes to withdraw by attacking East Anglia. After the Danes withdrew, Edward also retreated, but his Kentish vassals refused to retire and attacked the Danes in the Battle of the Holme in December of 892. In the ensuing battle, the Kentish forces lost the field, but both Aethelwold and Eohric were killed, and their Danelaw armies were forced to retreat; Aethelred and Aethelflaed returned to power in Mercia. Edward then built several fortresses across Wessex and Mercia to protect the Anglo-Saxon realms.

However, after the Norse were forced out of Dublin, Ireland in 902, a large group of Irish Viking exiles settled the lands to the north of the Mercian-held town of Chester, an old Roman fortress. The Mercians hoped for the Irish Vikings to act as a buffer against the Danelaw, but, by 907, the Irish Vikings had allied themselves with the Danelaw to besiege Chester. When the Mercian army went north to deal with the new threat, Aethelflaed led the army, as Aethelred was incapacitated due to illness. The Mercians defeated the Vikings at Chester, leaving Aethelflaed and Aethelred firmly in control. Aethelflaed then tutored Edward's son Aethelstan, who led a raid deep into Viking territory in 909, retrieving the relics of Oswald of Northumbria and pillaging the lands of Lindsay for five weeks before the Vikings in Jorvik could react. In 910, the Northumbrians retaliated by raiding deep into Mercia, ravaging the countryside. As they withdrew with their plunder, they were surprised at Tettenhall by a West Saxon-Mercian army, where their entire leadership was killed, crippling Jorvik for years to come. Around the same time, Aethelred passed away, and Aethelflaed was chosen as his successor as "Lady of the Mercians". Soon, she was forced to relinquish control of London to Wessex, and, over the next eight years, she built burhs to protect against the Welsh and the Danes, and fought endless wars along the Five Boroughs against the invading Danes of Leicester and Bedford.

Edward, meanwhile, was finally ready to counterattack against the Vikings from 911 to 913, moving them by land and sea into Essex and fortifying the town of Maldon. Wessex was finally gaining new lands, and Maldon became a base from which Edward could attack East Anglia. In 914, a massive Viking fleet conquered Brittany across the Channel, extinguished its ruling family, and, under the warlords Rold and Ottir, the Viking fleet sailed through the Bristol Channel and into the River Severn in an attempt to surprise the Mercians. However, Aethelflaed drove them out of Mercia and into Wales, killing Rold in the process. Edward pursued Ottir and his remaining vessels to the island of Flat Holm near Cardiff, and Ottir gave up on England and went across the sea to Ireland. By 914, Edward, too, was making inroads into the Five Boroughs, forcing of some of the Vikings of Bedford and Northampton to submit. By 917, Edward and Aethelflaed were prepared for their final assaults upon the Vikings. A large force of Danes from the Five Boroughs allied itself with the East Anglians, who attempted to mirror the success of the Anglo-Saxons by building their own burh at Tempsford in Bedfordshire. Within weeks, however, Edward's forces stormed the burh, killing the East Anglian king Guthrum II, and taking the whole of East Anglia and southeastern Mercia.

By mid-917, Aethelflaed marched her elite army across the border and besieged Derby. After a fierce battle, the town fell along with large swathes of eastern Mercia. By 918, Lester, Stamford, Nottingham, and Lincoln had also fallen, and Mercia completed its reconquest of the Five Boroughs. That summer, the Vikings of Jorvik agreed to submit to Aethelflaed, but she passed away that same year, and her child Aelfwynn of Mercia succeeded her. By 918, all of England south of the Humber was under Anglo-Saxon control. Edward marched north to Tamworth and seized Aelfwynn, placing her in a monastery and incorporating Mercia into his growing kingdom. Like Alfred before him, he achieved the fealty of the five Welsh kingdoms. Only Northumbria remained under Viking control in England, but, just as Edward was annexing Mercia, the Dublin Norse annexed Jorvik in a lightning attack, creating a new threat to England.